I believe they have what I would call more of a green tint kind of, a faint glow. Think jellyfish instead of glow stick. I don't think it's very visible. I've read blue light makes their glow stand out, but I haven't found concrete evidence on whether it hurt them or not.
I used a blue LED strip over my tank, barely hitting it as a night light and put it on over the tank before bed for night time viewing and my axolotl never reacted to it in any way. I would often find him near the cave closest to the blue LED light, where a bit of the light would go in, making me think he liked the blue light. After reading about the blue light possibly hurting them I stopped using it.